Device for monitoring penetration into anatomical members

ABSTRACT

The invention relates to a device that can be used to monitor the penetration of a penetration member into anatomical structures and, in particular, bone structures of a living body, the structures having at least two different electrical impedance areas. The device is characterized in that it comprises: at least one impedance meter which can be connected to at least two electrodes, at least one of the electrodes being located at a distal end of the penetration member; and at least one alert device which can produce an alert signal if the impedance meter detects an impedance variation. The invention also relates to a penetration member for the device and to an electronic board for the device.

BACKGROUND OF THE INVENTION

(1) Field of the Invention

The present invention relates to the field of the penetration ofmaterial, such as bone structures or the like, that exhibit differencesin intrinsic physical quantities.

The present invention relates more particularly to a device formonitoring the penetration of a penetrating means into anatomicalstructures, and especially bone structures, of a living body, saidstructures having at least two regions of different electricalimpedance.

(2) Prior Art

In spinal surgery, for example, when drilling the pedicle, it frequentlyhappens that the vertebral bone cortex is pierced, broken or chipped bythe penetrating drill bit. Depending on the authors, 15 to 40% ofpedicle screws are thus improperly positioned, with a clinicalmanifestation (pain, paralysis, hemorrhaging, etc.) in 1 to 2% of thecases and therefore require further intervention.

Surgeons sometimes use equipment such as the following:

-   -   equipment for surgical navigation, which is expensive and        cumbersome to implement;    -   equipment for monitoring of sensory and/or motor evoked        potentials, this being less expensive but also restricting as it        requires the presence of a specialist whose mission is solely to        carry out this monitoring operation.

As a result, in most cases the operators rely solely on their knowledgeof anatomy and their experience in order to accomplish this riskysurgical procedure.

The foregoing is also true in the case of other surgical fields.

In the field of drilling bone bodies, the prior art also includesinternational patent application WO 01/01875.

This patent application discloses a device that uses the ability ofnerves and muscles to transmit signals, in order to warn the user whenthe drilling means comes into contact with a nerve, so as to prevent anylesion of said nerve.

The prior art also teaches the use of impedance measurement in medicaldevices.

For example, the prior art includes the United States Patent U.S. Pat.No. 4,630,615 which relates to a neural stimulation system thatincorporates an apparatus for measuring or determining impedance inwhich it is desired to manage and determine the changes in impedance ina guide connected to a cathode implanted into the epidural space of aspinal column. Such a neural stimulation system is typically used whenit is desired to block off pain signals that are sent to the brain,which system may also be used for the treatment and/or relief ofsymptoms involving uncoordinated movements of the spinal column, such asepilepsy, spasticity, cerebral paralysis, etc.

The prior art also includes British Patent Application GB 2 335 990 thatrelates to a system for mechanical penetration of a needle and forstopping the penetration if a different impedance is detected at the endof the needle.

The object of that system is to inform the user when the end of theneedle has definitely reached the desired depth, either using animpedance value or using a change in impedance.

The object of that system is thus absolutely not to prevent a determineddepth being reached.

Furthermore, that system requires, for each patient, an experimentaldetermination of the impedance values or of the changes in impedance, asexplained on the last page of that application, which absolutely doesnot allow this system to be adapted for the purpose of preventing adetermined depth being reached.

The prior art also includes French Patent Application FR 2 101 911 whichrelates to an instrument for measuring the length of the root canal of atooth.

That instrument is used to deduce the length of a hollow body by thesubsequent measurement of the distance between two reference marks afterthese two reference marks have been placed into longitudinal abutment,respectively in the bottom of the tooth canal in the case of the probe,and the crown or the upper edge of the cavity in the case of the rubberpiece.

That instrument allows the user to be informed, after having made acavity, about the depth of this cavity; it does not allow real-timemonitoring of the penetration of a penetrating means into anatomicalstructures.

Another drawback of the techniques of the prior art is that arecumbersome to implement and tend to extend the operation time, thusincreasing the associated risks.

SUMMARY OF THE INVENTION

The present invention aims to remedy the drawbacks of the prior art byproposing a device that allows real-time monitoring of the penetrationof the penetrating means (the drilling means or the like) into thematerial, by measuring the differences in a physical quantity as thepenetration proceeds, so as to allow the user to know where the end ofthe penetrating means is and thus prevent any lesion.

The physical quantity used is the electrical impedance measurement.

It is important to point out that the use of the electrical impedancemeasurement may be applied to many different technical fields and notonly to the field of drilling bony bodies.

The present invention relates, in its widest sense, to a device formonitoring the penetration of a penetrating means as claimed in claim 1.

This device includes at least:

-   -   at least one impedance meter that can be connected to at least        two electrodes, at least one of which is located at a distal end        of said penetrating means, said impedance meter continuously        measuring the impedance between the two electrodes at least        during the penetration; and    -   at least one warning device capable of producing a warning        signal in the event of a change in impedance being detected by        the impedance meter.

In one embodiment, the device further includes an electrostimulatorcapable of producing a stimulation and able to be connected to at leasttwo electrodes, at least one of which is located at a distal end of saidpenetrating means.

In this embodiment, at least one electrode able to be connected to anelectrostimulator and at least one electrode able to be connected to animpedance meter are preferably connected together. Thus, it is the sameelectrodes that serve both for delivering the neuromuscular stimulationand for measuring the impedance.

Throughout the text that follows, the term “distal end” is understood tomean, of course, as in the case of any surgical instrument, the end withrespect to the handle used for holding the instrument, which is locatedat the proximal end.

Said warning signal is preferably a visual and/or audible and/or tactilesignal.

The neuromuscular stimulation produced by the neuromuscularelectrostimulator preferably has a frequency of less than or equal to 10Hz, a voltage of less than or equal to 4 volts and a pulse of durationof less than or equal to 400 μs.

In one embodiment, an electrode is formed by a contact surface locatedat the distal end of said penetrating means and another electrode isformed by a contact surface intended to be positioned on an externalsurface of the anatomical structures.

In another embodiment, said electrodes are each formed by a contactsurface respectively located at the distal end of said penetratingmeans, said contact surfaces being separated by an insulator.

In one version of this embodiment, the proximal electrode has a contactsurface greater in area than the contact surface of the distalelectrode.

In one embodiment, at least one distal electrode is formed by a contactsurface located on a partial peripheral portion of the distal end of thepenetrating means so as to make it possible to detect a change inimpedance in a direction approximately perpendicular to the axis ofpenetration of the penetrating means.

The device according to the invention preferably includes means forrotating said penetration means.

In one version of the invention, the impedance meter, the warning deviceand optionally the electrostimulator are positioned on a removableelectronic card, which includes means for connecting said electrodes, soas to allow the device to be sterilized independently of the electronicpart.

The device according to the invention preferably includes, for thispurpose, a hollow handle for accommodating said electronic card.

The present invention also relates to:

-   -   a fixed penetrating means, and especially a probe, squared tip,        spatula or curette, or    -   a penetrating means that can be rotated, and especially a drill        screw, drill tap or drill bit    -   for a device according to the invention.

The present invention also relates to an electronic card as definedabove for a device according to the invention.

This electronic card is preferably able to be sterilized and, alsopreferably, is placed in a casing that preserves sterility.

The present invention further relates to a manual or motor-operateddrilling instrument, especially for drilling the vertebral pedicle, saidinstrument including a penetrating means and a device for monitoring thepenetration of said penetrating means according to the invention.

Advantageously, the present invention allows the user to be informed inreal time of the progression of the penetrating means optionallyassociated with the drilling instrument.

Also advantageously, the electrode located upstream of the penetrationis positioned close to the mechanical penetration effect and thus makesit possible to obtain a very high sensitivity in detecting a change inimpedance.

Advantageously, the invention thus makes it possible to avoid completetranspiercing of the body to be penetrated or pierced, when this is notdesired, and in the case of penetration of a bone body, to prevent alesion of the tissues located beneath the bone body.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be more clearly understood with the aid of thedescription, given below purely by way of explanation, of one embodimentof the invention, with reference to the appended figures:

FIG. 1 illustrates a partial sectional view of an instrument fitted witha device according to the invention;

FIG. 2 illustrates a detailed sectional view of a first embodiment ofthe penetrating means in the form of a probe;

FIG. 3 illustrates a detailed sectional view of a version of the secondembodiment of the penetrating means in the form of a probe;

FIG. 4 illustrates a detailed sectional view of another version of thesecond embodiment of the penetrating means in the form of a probe;

FIG. 5 illustrates a sectional view of the penetration P of thepenetrating means of FIG. 2;

FIG. 6 illustrates a sectional view of the penetration P of thepenetrating means of FIG. 3;

FIG. 7 illustrates a sectional view of the penetration P of thepenetrating means of FIG. 4;

FIGS. 8 and 9 illustrate a front view and top view, respectively, of apenetrating means according to the invention formed by a spatula;

FIGS. 10 and 11 illustrate a front view and a top view, respectively, ofa penetrating means according to the invention formed by a curette;

FIG. 12 illustrates a detailed sectional view of a penetrating meansaccording to the invention formed by a drill bit, screw or tap; and

FIG. 13 illustrates two examples of the relationship between themeasured impedance Z in ohms and the frequency in hertz of an audiblesignal emitted by the warning device.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

The device (1) according to the invention, illustrated in FIG. 1, is adevice for monitoring the penetration of a penetrating means (2) intoanatomical structures, and especially bone structures (3) of a livingbeing, said structures having at least two regions of differentelectrical impedance (Z1, Z2).

For example, the penetrating means (2) makes it possible, itself orcombined with a drilling instrument, to drill a hole (20) in said bonestructures (3).

A bone body is composed of soft internal tissue (marrow, spongy bone)and hard external tissue (cortex); it is itself surrounded by softtissues: muscles, tendons, ligaments, blood vessels and nerves.

Owing to these differences in nature, the bone cortex has physicalproperties different from those of the tissues with which it is contact:it is for this reason that it is also visible in medical images:conventional radiography, scanner, echography, magnetic resonanceimaging.

If the instrument used to penetrate the bone cortex is fitted at itsdistal end with a means for detecting and indicating this difference inphysical properties, the operator will therefore immediately haveinformation informing him that he has passed through this cortex or thathe is about to do so.

However, it turns out that the bone cortex and the soft tissues alsohave different impedances.

In a base version, the device (1) according to the invention comprises:

-   -   at least one impedance meter (7) that can also be connected to        at least two electrodes, at least one of which is located at a        distal end of said penetrating means (2), said impedance meter        continuously measuring the impedance between the two electrodes        at least during the penetration; and    -   at least one warning device (8) capable of producing a warning        signal in the event of a change in impedance being detected by        the impedance meter (7).

Thus, thanks to the impedance meter (7), it is possible to monitor thepenetration of the detection means associated with the penetrating means(2) progressively as the latter penetrates into the bone structures (3).

The way in which the impedance meter or meters (7) are used to deducetherefrom the position of the associated detection means constitutes oneparticular method of monitoring the penetration of a penetrating means(2) through a body having at least two regions of different electricalimpedance (Z1, Z2).

The device (1) includes a warning device (8) which can emit:

-   -   a visual warning signal modulated, for example, by the use of a        flashing warning lamp or a ramp of warning lamps; and/or    -   an audible warning signal frequency-modulated and possibly        intensity-modulated, for example by the use of a loudspeaker;        and/or    -   A tactile warning signal frequency-modulated and possibly        intensity-modulated, for example by the use of a vibrator,    -   providing a warning right from the start of the change in        measured impedance and when a threshold of a change in measured        impedance is exceeded.

This modulated warning signal is proportional to the change inimpedance.

This warning device (8) is preferably positioned on or in theinstrument, as may be seen in FIG. 1.

The device (1) may optionally further include a display means fordisplaying the change or changes in impedance, which is connected to animpedance meter (7). This display means, formed for example by a displayscreen, makes it possible to monitor the variation, in the form ofcurves, of the change in impedance progressively with the penetration ofthe penetrating means (2).

In one embodiment, the device (1) further includes at least oneelectrostimulator (4), preferably a neuromuscular stimulator, capable ofproducing a preferably neuromuscular stimulation and able to beconnected to at least two electrodes (5, 6), at least one of which islocated at a distal end of said penetrating means (2).

The neuromuscular stimulation produced by the neuromuscularelectrostimulator has:

-   -   a frequency of less than or equal to 10 Hz, preferably around        2.5 Hz;    -   a voltage of less than or equal to 4 volts, preferably around 1        volt; and    -   a pulse of duration of less than or equal to 400 μs, preferably        around 150 μs.

In the event of the bone cortex being penetrated by the penetratingmeans, the distal portion (tip) of the latter comes into contact withthe soft tissues located on the outside of the cortical envelope. Thestimulation pulses may then propagate easily into these soft tissues oflow impedance and stimulate the nerves possibly located near the tip ofthe penetrating means. Two situations then arise:

-   -   a) if they are motor nerves, they will then cause contractions        of the muscle groups with which they are associated, at the rate        of the stimulation pulses; these contractions will be detected        and recognized, either by an electromyography connected up to        the patient beforehand, or clinically by the operator himself in        relation to the patient's movements;    -   b) if they are sensory nerves, a suitable device will be able to        detect their stimulation, which is also recognizable by its        rate.

In a preferred version of the invention, the electrodes (5, 6) may beconnected, using connection terminals (18), both to theelectrostimulator (4) and to the impedance meter (7). Thus, it is thesame electrodes that serve both for the emission of the neuromuscularstimulation and for the impedance measurement.

The penetrating means (2) of the device (1) may be:

-   -   either fixed, and consisting especially of a probe, a squared        tip, a spatula or a curette;    -   or capable of being rotated, and consisting especially of a        drill screw, a drill tap or a drill bit.

In the latter case, the device (1) then includes drive means (9) for therotation R of said penetrating means (2).

The drive means (9) consist, for example, of an electric motor capableof rotating the penetrating means (2) and form, in combination with thepenetrating means (2), a boring instrument (1) of the borer type.

In the section below, the penetrating means (2) is formed by a probe,but the configurations presented are applicable to any type ofpenetrating means (2).

In a first embodiment, illustrated in FIGS. 2 and 5, a distal electrode(5) is formed by a contact surface C located at the distal end of saidpenetrating means (2) and another, proximal electrode (6) is formed by acontact surface C′ intended to be positioned on an outer surface of theanatomical structures, including on the operation incision.

The penetrating means (2) has a central portion (15) that is conductingand a peripheral portion (13) that is insulated right to a distal end(14) bared, that is to say not insulated, over a few millimeters. Thesurface C has an area of less than 10 mm², around 4 mm², and the surfaceC′ has an area of around 20 mm².

Thus, the first pole of the electronic stimulation/measurement device isformed by the distal end of the penetrating means (2) of the instrumentand the other pole is formed by a reference connection on the patient.

In a second embodiment, illustrated in FIGS. 3 and 6 on the one hand and4 and 7 on the other, said electrodes (5, 6) are each formed by acontact surface C, C′ respectively, which is located at the distal endof said penetrating means (2), said contact surfaces C, C′ beingseparated by an insulator (12).

In the version illustrated in FIGS. 3 and 6, the penetrating means (2)comprises a conducting central portion (15) and a conducting outerportion (16), said central portion (15) and said outer portion (16)being separated by a cylindrical insulator (12). The two conductingportions each form one pole of the electronic device.

Thus, the outer portion (16) forms a conducting outer tube, hollow atits center, and the central portion (15) forms a conducting innercylinder, the central (15) and outer (16) portions both emerging at theend of the penetrating means (2) so as to form the two surfaces C and C′that are isolated from each other.

In this version, the proximal electrode (6) has a contact surface C′greater in area than the contact surface C of the distal electrode (5).The surface C has an area of less than 10 mm², around 4 mm², and thesurface C′ has an area of greater than 100 mm², around 400 mm².

In the version illustrated in FIGS. 4 and 7, the penetrating means (2)comprises an insulating peripheral portion (13) and a noninsulateddistal end (14), having two electrodes (5, 6) that are positioned so asto be perpendicular to the axis A of said penetrating means (2) andseparated by an insulator (12). The two electrodes (5, 6) each form onepole of the electronic device.

In this version, the electrodes (5, 6) have contact surfaces, C and C′respectively, of approximately the same area, less than 10 mm² andaround 4 mm². The contact surfaces C, C′ are separated by an insulator(12) of thickness less than or equal to 1 mm along an axis A ofpenetration of said penetrating means (2).

FIGS. 5, 6 and 7 illustrate one moment during the penetration P of thepenetrating means (2), during which a change in a physical quantity, andmore particularly a change in electrical impedance, is detected by theimpedance meter (7). Such a change occurs especially when thepenetrating means (2) leaves the cortex of the bone body, represented bythe region Z1, and penetrates a soft surrounding tissue, represented bythe region Z2.

In the embodiment that combines an impedance meter with anelectrostimulator, the stimulation pulses of the device have a waveform,a voltage and an intensity that are known; it is therefore possible todeduce therefrom the impedance measured by the electrodes associatedwith the device and in particular by the electrodes placed at the distalportion (the tip) of the penetrating means.

This “local impedance” information can then be converted into signalscapable of operating the warning device (8).

The penetrating means (2) may have one pair of electrodes or evenseveral pairs of electrodes.

For each pair of electrodes, at least one electrode is positioned at thedistal end (14) of said penetrating means (2).

In one embodiment, at least one distal electrode (5) is formed by acontact surface C located on a partial peripheral portion of the distalend of the penetrating means (2) so as to make it possible to detect achange in impedance in a direction approximately perpendicular to theaxis A of penetration of the penetrating means (2). Thus, by rotatingthe penetrating device (2) and, by observing the warning device (8), itis possible to deduce, from the measured change in impedance thanks tothis electrode, the configuration of the distal end of the hole (20).

In the section below, the penetrating means (2) is formed by a drillbit.

The penetrating means (2) is provided, for example, with a helicalthread (19) shown in FIG. 12, or with several helical threads, which areformed along the axis A so as to allow holes (20) to be drilled.

The drill bit comprises a conducting central portion (15) and aconducting helical thread (19), the central portion (15) and the helicalthread (19) being separated by a cylindrical insulator (12). The twoconducting portions each form one pole of the electronic device.

In this version, the proximal electrode (6) has a contact surface C′greater in area than the contact surface C of the distal electrode (5).The surface C has an area of less than 10 mm², around 4 mm², and thesurface C′ has an area of greater than 10 mm², around 40 mm². Thecontact surfaces C, C′ are separated by an insulator (12) of thicknessless than or equal to 1 mm along an axis A of penetration of saidpenetrating means (2).

This configuration is also applicable to a screw and especially to aself-drilling screw.

In one embodiment of the invention, the impedance meter (7) and thewarning device (8), or the impedance meter (7), the warning device (8)and the electrostimulator (4), are positioned on a removable electroniccard (10), visible in FIG. 1, which includes means for connecting saidelectrodes (5, 6). Thus, the mechanical part of the device (1) can besterilized in an autoclave, without the electronic part.

It is also possible to provide for the electronic card (10) to be ofone-time use—it is delivered in suitable packaging and is fitted by thesurgeon into the instrument that he requires (a probe, squared tip,spatula, curette, screw driver, borer, etc.) when he wishes to monitorthe progressive penetration of the associated instrument that he isusing. The electronic card (10) is thrown away after the operation,whereas the instrument is sterilized.

It is also possible to produce an electronic card (10) that can besterilized, especially by chemical action.

The electronic card (10) may also be positioned in a casing thatpreserves sterility.

To allow the electronic card (10) to be fitted into the instrument, thedevice (1) preferably has a hollow handle (11) into which the electroniccard (10) can be placed. Access to the inside of the hollow handle isgained by removing a plug (19).

The connection terminals (18) allow the electrodes to be connected. Theymay be positioned around the periphery of the handle (11), in order toconnect up one or more electrodes, and in the distal portion of thehandle relative to the plug (19), in order to allow the electrode(s)located at the distal end of the penetrating means (2) to be connected.

The electronic stimulation/measurement device positioned on theelectronic card (10) measures, during use of the instrument, theelectrical impedance between the two poles each formed by one electrodeand indicates (in an audible, visual or tactile manner) in real time thevalues and/or changes in said impedance, in particular in the event ofthe pedicle cortex being breached.

FIG. 13 shows two representations of the relationship between themeasured impedance, plotted on the x-axis, and the frequency of anaudible signal emitted by the warning device, plotted on the y-axis.This relationship may, for example, be linear, as illustrated by thediscontinuous line, or may be stepped. This relationship is obtainedwith surfaces C and C′ about 5 mm² in area.

In order to use the device according to the invention for boring, it maybe useful to provide a number, or set, of penetrating means (2), eachpenetrating means (2) of which has a different diameter.

The invention has been described above by way of example. Of course, aperson skilled in the art is capable of producing various alternativeembodiments of the invention without thereby departing from the scope ofthe patent.

1-17. (canceled)
 18. A drilling device for monitoring the penetration ofa penetrating means into a bone structure of a living being having atleast two regions of different electrical impedance, said devicecomprising at least one impedance meter that can be connected to atleast two electrodes, at least one of said electrodes being located at adistal end of said penetrating means, said at least one impedance metercontinuously measuring the impedance between the at least two electrodesat least during the penetration and at least one warning devicedelivering a warning signal modulated proportionally with the change inimpedance detected by the at least one impedance meter.
 19. The drillingdevice as claimed in claim 18, wherein said warning signal is amodulated visual warning signal.
 20. The drilling device as claimed inclaim 18, wherein said warning signal is a frequency-modulated audiblewarning signal.
 21. The drilling device as claimed in claim 18, whereinsaid warning signal is an intensity-modulated audible warning signal.22. The drilling device as claimed in claim 18, wherein said warningsignal is a frequency-modulated tactile warning signal.
 23. The drillingdevice as claimed in claim 18, wherein said warning signal is anintensity-modulated tactile warning signal.
 24. The drilling device asclaimed in claim 18, wherein said warning signal is an audible signalhaving a frequency that is a linear function of the measured impedance.25. The drilling device as claimed in claim 18, wherein said warningsignal is an audible signal having a frequency that is a steppedfunction of the measured impedance.
 26. The drilling device as claimedin claim 18, further including at least one electrostimulator capable ofproducing a stimulation and able to be connected to the at least twoelectrodes.
 27. The drilling device as claimed in claim 26, wherein atleast one first electrode is connected to said at least oneelectrostimulator and at least pne second electrode is connected to animpedance meter.
 28. The drilling device as claimed in claim 26, whereinneuromuscular stimulation produced by the at least one electrostimulatorhas a frequency of less than or equal to 10 Hz, a voltage of less thanor equal to 4 volts, and a pulse of duration of less than or equal to400 μs.
 29. The drilling device as claimed in claim 18, wherein oneelectrode is formed by a contact surface located at the distal end ofsaid penetrating means and in that another electrode is formed by acontact surface intended to be positioned on an external surface of ananatomical structure.
 30. The drilling device as claimed in claim 18,wherein said electrodes are each formed by a contact surfacerespectively located at the distal end of said penetrating means, andsaid contact surfaces being separated by an insulator.
 31. The drillingdevice as claimed in claim 21, wherein a proximal electrode has acontact surface greater in area than a contact surface of a distalelectrode.
 32. The drilling device as claimed in claim 18, wherein thepenetrating means comprises a conducting central portion and aconducting outer portion, said conducting central portion and saidconducting outer portion being separated by a cylindrical insulator, theconducting outer portion forming a conducting outer tube, hollow at itscenter, and the conducting central portion forming a conducting innercylinder, and the conducting central and outer portions both emerging atthe end of the penetrating means so as to form two surfaces that areisolated from each other.
 33. The drilling device as claimed in claim18, wherein a proximal electrode has a first contact surface greater inarea than a second contact surface of a distal electrode and in that thefirst contact surface has an area of less than 10 mm², and the secondcontact surface has an area of greater than 10 mm², the contact surfacesbeing separated by an insulator having a thickness less than or equal to1 mm along an axis of penetration of said penetrating means.
 34. Thedrilling device as claimed in claim 33, wherein the first contactsurface has an area around 4 mm² and the second contact surface has anarea around 40 mm².
 35. The drilling device as claimed in claim 18,wherein at least one distal electrode is formed by a contact surfacelocated on a partial peripheral portion of the distal end of thepenetrating means so as to make it possible to detect a change inimpedance in a direction approximately perpendicular to an axis ofpenetration of the penetrating means.
 36. The drilling device as claimedin claim 18, wherein said device includes means for rotating saidpenetrating means.
 37. The drilling device as claimed in claim 18,wherein the at least one impedance meter, the at least one warningdevice and optionally an electrostimulator are positioned on a removableelectronic card, which card includes means for connecting saidelectrodes.
 38. The drilling device as claimed in claim 37, wherein saiddevice includes a hollow handle for accommodating said electronic card.39. A fixed penetrating means and especially a probe, squared tip,spatula or curette, or a penetrating means that can be rotated, andespecially a drill screw or drill bit, for a drilling device as claimedin claim 18, wherein it includes at least one electrode.
 40. A manual ormotor-operated drilling instrument, especially for drilling thevertebral pedicle, said instrument comprising a penetrating means, and adevice for monitoring the penetration of said penetrating means asclaimed in claim
 18. 41. An electronic card for a device as claimed inclaim 37, which includes means for connecting at least two electrodes.42. The electronic card as claimed in claim 41, which card can besterilized.
 43. The electronic card for a device as claimed in claim 42,wherein said card is positioned in a casing that preserves sterility.